Exercise begins with 'explosion' on Portland bridge

Police scanners began crackling with reports of an explosion on the Steel Bridge this morning as part of a massive terror drill that will run in Portland over the next three days.

The first broadcasts went out at 9:08 a.m., with dispatchers talking about a truck exploding next to a MAX train on the bridge, which spans the Willamette in downtown Portland. Those broadcasts were followed by reports of the train going into the river; floating bodies; and related disasters.

All the broadcasts were related to a drill called Topoff 4, the largest counterterrorism drill in history. Along with Portland, similar drills are going on in Phoenix and Guam.